Granular Synthesis draws on the principle of amplitude synthesis (since a sound demands the addition of perhaps thousands of grains) and also offers possibilities for sound transformation. In addition to the direct synthesis of grains, acoustic sounds can be 'granulated', and the parameters of pitch and time then separated as in phase vocoding. One of the first composers to use the technique was the American Curtis Roads, who in the course of a series of experiments starting in 1975 composed several pieces using the technique either in part or, in the case of 'Prototype' (1975), throughout. More recent research by Barry Truax has concentrated on methods of controlling granular synthesis in real time. (Source - Richard Dobson (1992). A Dictionary of Electronic and Computer Music Technology. Oxford University Press.)